The effects of tryptophan depletion on cognitive and affective processing in healthy volunteers

RATIONALE: Cognitive impairment is a common feature of depressive illness. While accumulating evidence suggests that brain serotonin (5-HT) pathways play an important role in the neurobiology of depression, the extent to which altered 5-HT function is responsible for the associated changes in cognition and emotion remains unclear. OBJECTIVE: The present study examined the effects of acute dietary depletion of tryptophan (TRP) on cognitive and affective processing in healthy volunteers and explored the putative role of 5-HT in the neuropsychology of depression. METHODS: We administered computerised cognitive tests to healthy control participants following ingestion of TRP-free and nutritionally balanced amino acid drinks in a double-blind, placebo-controlled, crossover design. RESULTS: The TRP-free amino acid mixture significantly lowered plasma total and free TRP concentrations relative to baseline values and produced selective deficits similar to those observed previously in cases of clinical depression. In particular, TRP depletion increased response times for happy but not sad targets in an affective go/no-go task and slowed responding in a visual discrimination and reversal learning task. These deficits were not due to a global sedative effect, as planning ability was unimpaired. CONCLUSIONS: The present data indicate that serotonergic factors may be more involved in the disrupted inhibitory and emotional processing characteristic of depression than in other aspects of executive function, such as planning ability. These findings support the recent proposal that serotonergic manipulation may have greater effects on tasks mediated by frontal circuitry that includes the orbitofrontal cortex than by dorsolateral prefrontal cortex circuitry.     

Strengthening primary health care: building the capacity of rural communities to access health funding

ABSTRACT: Present health funding models can place onerous pressures on rural health services. Staff may lack the time, resources, access to data, and the expertise needed to complete complex and lengthy funding submissions. This present study describes an innovative capacity-building approach to working with Victorian rural communities seeking to access health care funding through the Regional Health Services Program. This approach used several strategies: engaging stakeholders in targeted rural communities, developing an information kit and running a workshop on preparing submissions to the Regional Health Services Program, facilitating community consultations, and providing ongoing support with submissions. Six rural communities were supported in this way. Four have been funded to date, with a combined annual recurrent budget for new primary health care services of over $2.5 million. Each community has developed a service delivery model that meets the particular needs of their local area. This capacity-building approach is both effective and replicable to other health funding opportunities.     

Investors in people: progress in the PHLS

In 1990 the government launched an initiative called Investors in People (IIP). The intention was clear: to improve operational performance in the workplace through effective business-focused training and development of employees. The market for the national standard that was created was also clear: every organisation throughout the UK, irrespective of size or sector. Implementation of IIP by the Public Health Laboratory Service (PHLS) is outlined, and four views of the process from across the Service are presented.     

Synthesis and protein kinase inhibitory activity of balanol analogues with modified benzophenone subunits

A series of analogues of the protein kinase C (PKC) inhibitory natural product balanol which bear modified benzophenone subunits are described. The analogues were designed with the goal of uncovering structure-activity features that could be used in the development of PKC inhibitors with a reduced polar character compared to balanol itself. The results of these studies suggest that most of the benzophenone features found in the natural product are important for obtaining potent PKC inhibitory compounds. However, several modifications were found to lead to selective inhibitors of the related enzyme protein kinase A (PKA), and several specific modifications to the polar structural elements of the benzophenone were found to provide potent PKC inhibitors. In particular, it was found that replacement of the benzophenone carboxylate with bioisosteric equivalents could lead to potent analogues. Further, a tolerance for lipophilic substituents on the terminal benzophenone ring was uncovered. These results are discussed in light of recently available structural information for PKA.     

Oxidized phospholipids derived from ozone-treated lung surfactant extract reduce macrophage and epithelial cell viability

Ozone is known to be a highly toxic gas present in the urban air which exerts its effect on pulmonary tissue through its facile chemical reactions with target molecules in the airway. One of the first barriers encountered by ozone is epithelial lining fluid which contains pulmonary surfactant rich in glycerophosphocholine lipids. The reaction of ozone with calf lung surfactant extract was found to result in the production of 1-palmitoyl-2-(9'-oxo-nonanoyl)-glycerophosphocholine (16:0a/9-al-GPCho) as an expected product of the ozonolysis of abundant unsaturated phospholipids containing unsaturated fatty acyl groups with a double bond at carbon-9. This oxidized phospholipid was identified as a biologically active product in that it reduced elicited macrophage viability by necrosis with an ED(50) of 6 microM. Further studies of the biological activity of 16:0a/9-al-GPCho revealed that concentrations from 100 to 200 nM initiated apoptosis in pulmonary epithelial-like A549 cells as assessed by TUNEL staining, nuclear size, and caspase-3 activation with loss of viability indicated by reduction of mitochondrial dehydrogenase activity. The release of IL-8, a neutrophil chemokine, from A549 cells was also stimulated by 50-100 nM 16:0a/9-al-GPCho. Exposure of calf lung surfactant to low levels of ozone (62.5, 125, and 250 ppb) for various time periods from 2 to 48 h in a feedback-regulated ozone exposure chamber resulted in a dose- and time-dependent increase in the formation of 16:0a/9-al-GPCho as measured by a specific and sensitive LC/MS/MS assay. The quantity of this biologically active chain-shortened glycerophosphocholine lipid generated even at 125 ppb ozone for 2-4 h (50-100 nM) was consistent with this product mediating the toxic effects of ozone on cells in contact with surfactant.     

Topiramate attenuates self-injurious behaviour in Prader-Willi Syndrome

Self-injurious behaviour (SIB), most notably skin picking, has been described by various terms in the literature ranging from neurotic/psychogenic excoriations to compulsive/pathological skin picking. Prader-Willi Syndrome (PWS) is a neurogenetic multisystem disorder characterized by infantile hypotonia, mental retardation, short stature, hypogonadism, dysmorphic features, and hyperphagia with a high risk of obesity. Psychiatric manifestations include SIBs in the form of skin picking, nail biting and rectal gouging. Topiramate is a novel anti-epileptic medication without significant liability of weight gain. There are no published reports of topiramate being utilized in PWS or SIB. We report attenuation of SIB with resultant lesion healing in three PWS adults treated with topiramate in an 8-wk open-label trial. Although our findings should be treated with caution, they suggest that double-blind or cross-over studies with topiramate are warranted to establish the possible role of topiramate in attenuating SIB in PWS and other disorders that involve SIB.